package com.neusoft.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;

/**
 * <br>描述：本类：产生验证码图片
 * */
public class VerifyServlet extends HttpServlet {

    /**
	 * 产生验证码图片
	 */
	private static final long serialVersionUID = 1L;
	//private static final String CONTENT_TYPE = "image/jpeg; charset=GBK";
    static Logger log = Logger.getLogger(VerifyServlet.class.getName());
        
    public void doGet(HttpServletRequest request, HttpServletResponse response) 
    {
		response.setHeader("Pragma","No-cache");
	    response.setHeader("Cache-Control","no-cache");
	    response.setDateHeader("Expires", 0);

//	    在内存中创建图象
	    int width=60, height=20;
	    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

//	    获取图形上下文
	    Graphics g = image.getGraphics();

//	    生成随机类
	    Random random = new Random();

//	    设定背景色
	    g.setColor(getRandColor(200,250));
	    g.fillRect(0, 0, width, height);

//	    设定字体
	    g.setFont(new Font("Times New Roman",Font.PLAIN,18));

//	    画边框
//	    g.setColor(new Color());
//	    g.drawRect(0,0,width-1,height-1);


//	    随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
	    g.setColor(getRandColor(160,200));
	    for (int i=0;i<155;i++)
	    {
	    int x = random.nextInt(width);
	    int y = random.nextInt(height);
	           int xl = random.nextInt(12);
	           int yl = random.nextInt(12);
	    g.drawLine(x,y,x+xl,y+yl);
	    }

//	    取随机产生的认证码(4位数字)
	    String sRand="";
	    for (int i=0;i<4;i++){
	       String rand=String.valueOf(random.nextInt(10));
	       sRand+=rand;
	       // 将认证码显示到图象中
	       g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
	       g.drawString(rand,13*i+6,16);
	    }

//	    将认证码存入SESSION
	    request.getSession(true).setAttribute("verify",sRand);
	    
//	    图象生效
	    g.dispose();

//	    输出图象到页面

	    try {
			ImageIO.write(image, "JPEG", response.getOutputStream());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
    }

   	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {this.doGet(request, response);	}
	
	private Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        Random random = new Random();
        if(fc>255) fc=255;
        if(bc>255) bc=255;
        int r=fc+random.nextInt(bc-fc);
        int g=fc+random.nextInt(bc-fc);
        int b=fc+random.nextInt(bc-fc);
        return new Color(r,g,b);
        }
}